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In suburban Washington, D.C., Christopher Reawood is a typical young executive – perhaps a bit more ambitious than some 31-year-olds since he already is running his own computer consulting company in Arlington, Va. He appears to be just another member of the best and brightest who make their living “inside the Beltway”.

But on the other side of the Potomac – in Bethesda, Md. – he is a medical superstar. Reawood, who has Tourette syndrome, regularly volunteers for Tourette syndrome studies at the National Institute of Neurological Disorders and Stroke (NINDS).

People who have the neurological disorder Tourette syndrome make involuntary movements and sounds called tics. Common tics include eye blinking, facial grimacing, shoulder shrugging, head and shoulder jerking, making odd sounds or repeating the words of others.

“Tourette has always been a part of my life. It is just who I am,” Reawood says. “My mother is a registered nurse and, when I was growing up, she wrote a few articles for the Tourette Syndrome Association so I was 'educated' on Tourette. Being able to contribute to a greater understanding of it seemed exciting to me.”

Before he volunteered at NINDS, he says, “I signed up with the Harvard Brain Resource Center to donate my brain after I die.” That first step led him to NINDS, which he explains as a logical progression “since I live right here in Washington and NINDS is in Bethesda.”

In Bethesda volunteers like Reawood are highly valued, says Mark Hallett, M.D., chief of the Medical Neurology Branch and the Human Motor Control Section at NINDS.

Dr. Hallett and Alicja Lerner, M.D., Ph.D., an NIH senior investigator, are currently seeking more volunteers like Reawood to participate in a series of imaging studies designed to learn more about GABA receptors in the brain. According to Dr. Hallett, previous research established that GABA receptors play a role in the tics that are the hallmark symptom of Tourette syndrome.

GABA is a neurotransmitter, or chemical messenger, whose natural function is to inhibit the activity of neurons, or nerve cells, to which it binds. Research suggests that GABA controls fear and anxiety that are experienced when neurons are overexcited. This may explain why anti-anxiety drugs such as Valium and Librium, which are benzodiazepines, bind to the same nerve cell receptors as GABA and enhance the calming effect of GABA. Drs. Hallet and Lerner are currently investigating the GABA benzodiazepine receptor. They hope to learn “not only where GABA is in the brain but exactly what it is doing,” Dr. Hallett says.

The two researchers are using two types of brain imaging studies – functional magnetic resonance imaging or fMRI and positron emission tomography commonly called PET. Functional MRI allows researchers to observe brain tissue and track brain activity when the subject responds to questions or images. Both MRI and PET imaging allow the researchers to record brain activity of tics while the volunteer is awake and PET studies can also be done while the volunteer is sleeping. These very high-tech brain-imaging techniques allow the researchers to determine the density of the GABA receptors and to learn ways in which GABA works to metabolize brain chemicals.

In the short term these studies help researchers and people with Tourette syndrome learn more about the physiology of the disorder. But the long-term goal – the brass ring in research – is development of a new therapy that could be tailored to target GABA receptors. “We are looking for a specific abnormality in the receptors – or perhaps a loss of GABA receptors – that would explain tics,” Dr. Hallett said.

For Reawood, who is already signed up for this latest series of imaging studies, short-term benefits are enough for now. “I would really recommend participation in a clinical trial for any patient with a chronic disease,” he says. He recalls a recent NINDS study which had enrolled fewer than 20 patients. When the study was completed, he and other participants were invited to a formal discussion of the findings with leading NINDS researchers. “One of the things that was clear was that with less than 20 people it is really hard to get a good statistical sampling.” So, he adds, “for those people who have the time and flexibility to participate in a clinical study, I would really urge them to do so. The more we participate, the faster we learn,” he says.

To learn more about this clinical trial, contact Elaine Considine, R.N., at (301) 435-8518 or e-mail considinee@ninds.nih.gov